It has been the practice in certain centrifugal or axial flow pumps to provide a bushing or bearing for supporting the pump impeller mounting end of a pump shaft at the point it passes through a pump backplate or stuffing box cover.
Typically, bushings used for supporting pump shafts in this manner are sleeve bushings formed of graphite or other suitable bearing material, which are force fitted within a pump shaft access or through opening defined by a pump backplate. Alternatively, bushings are supported within bushing holders, which are force fitted within such access opening.
It is desirable to permit inspection of such bushings for evidence of wear or deterioration in order to permit bushing replacement before total failure. However, there has heretofore been no way of gaining access to such bushings for inspection and/or replacement purposes without first effecting complete removal and disassembly of the pump rotating assembly including for example the pump shaft, impeller, backplate or stuffing box cover and gland or seal chamber housing. It is normally very inconvenient to disassemble a pump rotating assembly in the field or at the point of pump installation, and thus it has been the practice to transport the assembly to a workshop or area designated for maintenance purposes. Thus, a decided drawback of present practice is the time and expense required to effect inspection and/or replacement of pump shaft supporting bushings of the type described.